1、AECMA STANDARD NORME AECMA AECMA NORM Edition approved for publication 1995-1 2-1 5 prEN 6034 Edition PI December 1995 AIBITFG Chairman Mr K. Schneider Comments should be sent within six months after the date of publication to AECMA Gulledelle 94 6-1 200 BRUXELLES PUBLISHED BY THE EUROPEAN ASSOCIATI
2、ON OF AEROSPACE INDUSTRIES (AECMA) Guiledelle 94 - 8-1200 BRUXELLES - Tel. (32) 2 775 81 10 - Fax. (32) 2 775 81 11 ICs : Descriptors : ENGLISH VERSION Aerospace series Carbon fibre reinforced plastics Test method Determination of interlaminar fracture toughness energy Mode II - GIIC Srie arospatial
3、e Matires plastiques renforces de fibres de carbone Mthode dessai Dtermination de lnergie de tnacit en rupture interlaminaire Mode II - GIIC Luft- und Raumfahrt Kohlenstoffaserverstrkte Kunststoffe Prfverfahren Bestimmung der interlaminaren Energiefreisetzungsrate Mode II - GI, This “Aerospace Serie
4、s“ Prestandard has been drawn up under the responsibility of AECMA (The European Association of Aerospace Industries). It is published on green paper for the needs of AECMA-Members. It has been technically approved by the experts of the concerned Technical Committee following comment by the Member c
5、ountries. Subsequent to the publication of this Prestandard, the technical content shall not be changed to an extent that interchangeability is affected, physically or functionally, without re-identification of the standard. After examination and signature of the AECMA Standard Checking Centre (NPS)
6、 and formal agreement of the Official Services of the Member countries it will be submitted as a draft European Standard to CEN (European Committee for Standardization) for formal vote. - AECMA PREN+b034 95 = 10123Ll OOLOL59 867 = Page 2 prEN 6034 : 1995 Contents list 1 2 3 4 5 6 7 8 9 10 Scope Norm
7、ative references Definitions Principle of the method Designation of the method Apparatus Test specimen Procedure Presentation of the results Test report Page 3 prEN 6034 : 1995 1 Scope This standard specifies the procedure to determine the mode II interlaminar fracture toughness energy GI, of carbon
8、 fibre composites manufactured from unidirectional fibre tape or woven fabric. This standard does not give any directions necessary to meet health and safety requirements. It is the responsibility of the user of this standard to consult and establish appropriate health and safety precautions. 2 Norm
9、ative references This European Standard incorporates by dated or undated reference, provisions from other publications. These normative references are cited at the appropriate places in the text and the publications are listed herafter. For dated references, subsequent amendments to or revisions of
10、any of these publications apply to this European Standard only when incorporated in it by amendment or revision. For undated references, the latest edition of the publication referred to applies. EN 2565 Aerospace series Preparation of carbon fibre reinforced resin panels for test purposes I EN 2743
11、 Aerospace Series Reinforced Plastics Standard procedures for conditioning and testing ” EN 2823 Aerospace series Fibre reinforced plastics Test method for the determination of the effect of exposure to humid atmosphere on physical and mechanical characteristics - Parameters for conditioning and tes
12、ting ” EN 6033 Carbon Fibre Reinforced Plastics Determination of interlaminar fracture toughness energy - Mode I - Glc-test 3 Definitions 3.1 Interlaminar fracture toughness energy The interlaminar fracture toughness energy is the energy per unit plate width which is necessary to produce an unit cra
13、ck growth at an interlaminar crack between two plies of a laminate. 3.2 Mode II The mode indicates the method by which the load is applied to produce the crack. Mode II crack extends as a result of shear forces at the crack tip introduced by a flexural test. 3.3 GI, GI, is the designation of the int
14、erlaminar fracture toughness energy determined by a mode II test procedure. I Published as AECMA Prestandard at the date of publication of this standard AECMA PRENMb034 95 W LOL23LL OOLOLb1 415 = Description block Carbon fibre reinforced plastic materials Page 4 prEN 6034 : 1995 Identity block EN t
15、334 - 4 Principle of the method The end notched flexure specimen is used for mode II testing. A precracked specimen is loaded in a three point bend fixture (see figure 21 until crack propagation onset. The load applied to the specimen and the cross head displacement of the test machine are recorded
16、continuously during the test. The total fracture toughness energy is calculated from the initial crack length and load-displacement diagram. 5 Designation of the method Number of this standard 6 Apparatus 6.1 Test machine accurate to within 1 % in the load range used. 6.2 Device for recording the de
17、flection as a function of load accurate to within 1 % in the deflection range used. 6.3 Vernier caliper accurate to the nearest 0,l mm. 6.4 Flat face micrometer accurate to the nearest 0,Ol mm 6.5 Microscope of a magnification of 15 - 25 7 Test specimen 7.1 Test specimen description To achieve repro
18、ducable test results the G,-test shall only be performed with specimens (see figure 1) where the initial crack has been introduced in a defined mode I procedure (see EN 6033). The test specimen shall be cut from the residual part of G, specimen tested or at least loaded and cracked per EN 6033, and
19、fulfilling the following requirements. 7.2 Test specimen preparation Prepare the required laminates according to EN 2565 method B for carbon. The crack front remains approximately a straightline perpendicular to the longitudinal direction of the specimen (as presumed by the marks performed on both a
20、lready painted longitudinal side faces of the specimen to locate the crack tips after crack stabilization unter the mode I loading). The uncracked portion of the specimen is of sufficient length to comply with the requirements of figure 1. - AECMA PREN*b034 95 1012311 0010162 351 Page 5 prEN 6034 :
21、1995 The observation during the mode I loading did not show neither fibre bridgings nor moving of the crack to plies adjacent to the mid plies. The specimen shall be cut in a way that the specified remaining crack length of figure 1 is guaranteed. Specimens longer than 1 12 mm can be used to realize
22、 a serie of tests for the determination of GlIc if needed. Appropriate identification shall be maintained throughout the specimen preparation to ensure traceability to the GI, specimen and to the original laminate. If not otherwise defined by the specification invoking the test, three specimens shal
23、l be tested per test condition. CAUTION: When testing fabric material, the results may be influenced by the position of the crack between the layers (nested, unnested etc.). It shall be clearly stated which interlaminar area shall be tested and how to manufacture the specimens. 8 Procedure 8.1 Condi
24、tioning If not otherwise defined by the specification invoking the test, specimens to be tested dry or in the as cured state , should first be conditioned at (23 f 2)OC, (50 f 51% RH in accordance with EN 2743, same requirements to be applied to perform room temperature testing. Aged specimens shall
25、 be tested directly after ageing procedure (a maximum storage of 8h at (23 f 2C is allowed before testing). 8.2 Determination of dimensions The width and length of the specimens shall be measured using a vernier caliper (see 6.3). A minimum of three thickness measurements distributed over the specim
26、en shall be made using a flat face micrometer of 6.4, the average shall be recorded. 8.3 Testing the crack length has to be measured by vernier caliper (see 6.31, using the microscope (see 6.51. A thin layer of white ink applied to the longitudinal side faces of the specimen may be used to facilitat
27、e this measurement. For the entire duration of the test, a continuous load-displacement record shall be made, measuring the displacement of the loading nose. Place the specimen in the test fixture in accordance with figure 2, assuring the position of the initial crack : a = (35 t llmm. The following
28、 procedure shall then apply: Adjust the load cell reading at zero Remove any slack between the loading nose and the specimen by making the needed displacement - Adjust the displacement reading at zero if necessary - - AECMA PRENxb034 95 = LOL23LL OOLOLb3 298 9 Page 6 prEN 6034 : 1995 Adjust the disp
29、lacement reading at zero if necessary Load the specimen under displacement control at a displacement rate of 1 mm/min Optically observe the crack tip in order to detect the crack propagation onset (microscope of 6.5) Record the critical load at delamination crack onset and stop the loading as soon a
30、s evidence of crack propagation has been confirmed by a small load drop 8.4 Elevated and sub-zero temperature tests If not otherwise defined by the specification invoking the test, apply a thermocouple on the specimen as close as possible to cracked area of the specimen and seal the thermocouple fro
31、m the surrounding air by using vacuum bag sealant. The soak time at test temperature, defined by the specification invoking the test, shall be (5 & 0,5)min for dry specimens and in accordance with EN 2823 for conditioned specimen. If more then one determination is provided for, wait for crack stabil
32、ization under load and mark the current tip location on the painted sides of the specimen Unload the specimen to zero The complete procedure shall be repeated for the subsequent determinations when needed. Unless otherwise specified, the remaining uncracked portion of the specimen shall be delaminat
33、ed after removal from the test fixture (cooling the specimen down to liquid nitrogen temperature will facilitate this operation). Verification measurements of the crack lengths shall then be made from the crack front (thumbnail marks) on the fractured specimen. Care shall be taken to protect the del
34、amination surfaces for later inspection of failure mode if requested. The results shall be analysed in accordance with 9. 9 Presentation of the results 9.1 Calculation To calculate GI, the following formula shall be used : 9 x P x a x d x 1000 2xw (1/4 L3 + 3a3) - G IIC - where : GIIC d P a W L is t
35、he fracture toughness energy, in J/mZ is the crosshead displacement at crack delamination onset, in millimetres is the critical load to start the crack, in Newton is the initial crack length (see figure 21, in millimetres is the width of the specimen, in millimetres is the span length (see figure 21
36、, in millimetres AECMA PREN*b034 95 LOL23LL 0010164 124 m Page 7 prEN 6034 : 1995 9.2 Test results validation The test results and calculation shall be valid if the crack front is approximately perpendicular to the specimen longitudinal direction and does not extensiveley change from a straigthline
37、across the width of the fractured test specimen. 10 Test report The test report shall refer to this standard and include the following : 10.1 10.2 10.3 10.4 10.5 10.6 10.7 10.8 Complete identification of the tested material, including manufacturers name, designation, batch number etc. All details ab
38、out the preparation of specimens Measured dimensions of the specimens Ageing and/or exposure conditions prior to the test Date of test, facility and identification of individuals performing the test Equipment, method and test parameters used Individual test results and calculations plus a typical se
39、t of load-displacement curves. The individual curves shall be kept in file by the test laboratory. Any incident which may have effected the results and any deviation from this standard. Movement of the crack to plies adjacent to the mid plies shall be reported. Page 8 prEN 6034 : 1995 a cuts from G, specimen loading nose (steel) - I r, = 12,5 2 0,l rfl I 1 -5 I -m “t / I 110 mm (25,O -L 0,2) mm (3,O I O,2) mm (40 f 1) rnrn - I - W t - C - - Figure 1 : Test specimen support (steel) r2 = 5,O = 0,l - u2 I L = 100 t 0,5 All dimensions in mm Figure 2 : Test fixture
